A java object within a hibernate application can be in one of the three states:

1. New/transient

2. Attached/persistent

3. Detached

Important points about object states in Hibernate

• When an object is created, it will be in the new/transient state.

  • Hibernate will not save any updates to the transient objects.

• When you do a get, save, update or delete from within a session transaction, the object moves to the persistent state.

  • Now the object will be attached to the session and any changes will be tracked by hibernate.

• Finally when you do a session.commit(), object moves to the detached state, doing the following:

  • Hibernate will save the latest version of the object.

  • The object is detached from the session.

• Hibernate will not save any updates to the detached objects, until they are attached again to a session.

Example

Make below modifications over the lab excercise done @ http://javajee.com/lab-your-first-hibernate-43-program

Make below modifications in the test class alone:

Initially we created an object and gave values as:

User u = new User();

u.setId(1);

u.setName("Heartin");

Later we save it within a session as:

session.beginTransaction();

session.save(u);

session.getTransaction().commit();

Modify the object after session.save as:

session.beginTransaction();

session.save(u);

u.setName("Heartin.Jacob");

session.getTransaction().commit();

If you execute the same program now, you can see that, the value of the name field is updated to Heartin.Jacob, even though there is no explicit save command.